System and method for forming elongated perforations in an inner barrel section of an engine

An acoustic inlet barrel of an engine (e.g. aircraft gas turbine). The acoustic inlet barrel comprises an inner barrel 120 directing airflow through the engine and an inner face sheet 134 separated from an outer face sheet (132, figure 4) by an acoustic core 128. A plurality of elongated, non-circular perforations 136 are formed through the inner face sheet 134. The perforations 136 (e.g. teardrop, elliptical, diamond, dogbone or barbell shaped) may be elongated slots having longitudinal axis aligned with a flow contour line of the airflow. A method of forming an engine component (e.g. translating sleeve, inner wall) comprises sandwiching an acoustic core 128 between inner 134 and outer (132, figure 4) component sections and forming a plurality of elongated, non-circular perforations 136 in the inner portion 134. A forming system (200, figure 5) comprising at least one robotic forming unit 208 including at least one (e.g. drill or mill) end effector 234 positioned inside a barrel section is disclosed. The forming unit may index a pattern of perforations to a composite honeycomb core cell wall, forming perforations such that the perforations are spaced from cells walls (see figure 11).